Logitech International SA

U.S. stocks slumped, sending the Dow Jones Industrial Average toward its biggest drop since September, and Treasuries rose after a gauge of China’s manufacturing shrank. Emerging-markets stocks fell while gold and natural gas rallied.

The yen weakened for the first time in four days against the dollar as Japan’s deputy economy minister backed further declines. The Standard & Poor’s 500 Index fluctuated near a five-year high while Apple Inc. tumbled.